Back in october I harvested wild yeast from some wines grapes I'm growing in my yard, I brewed a small batch with it and it turned out well so I saved the trub/yeast from that batch in the fridge.

I recently woke the yeast up from itís cold storage slumber with some yeast nutrient/energizer and sugar water. That took off pretty well and the yeast set about consuming all of the sugar and flocculating out fairly quickly.
A little later I wanted to re-energize the yeast to contribute it to a batch of Wisconsin Weizen Beer being made as part of Discovery World Museumís Ale through the Ages program. I used a turkey baster to suck out the fermented liquid above the layer of yeast sediment on the bottom of my container. I dumped this liquid into a beer glass and refilled the container with warm sugar water to wake the yeast back up.

Then I neglected to dump out the beer glass containing the spent water. I tasted it and it tasted kind of like those ice beers that were all the rage in college, slightly beerish taste from the original batch of beer I brewed and high alcohol from the fermented out sugar water I added. There was a tiny bit of yeast sediment on the bottom from when I accidentally sucked some off with the baster. The liquid was clear.

Hereís where I admit to my colossal laziness. After about a week of sitting on my desk doing nothing I noticed that a small bit of the surface of the beer had an extremely thin film on it. Over the next day or two I watched as this thin film spread across the surface. After it had conquered the surface of the beer the film started to appear wrinkly and I took some photos.
It didnít smell like anything other than beer. So I left it to see what would happen.

Itís now been nearly two weeks since I filled the cup with this beerwater and the pellicle has thickened up quite a bit. I took some more photos.
As you can see itís yeast colored and looks like a creepy brain, itís about an eighth of an inch thick. The smell is of beer and yeast. Nothing sour or nasty. Which is a bit baffling considering this is sitting in an open to the air cup where any contaminant organism could easily fall in there.
The beer I made two weeks ago with the wild yeast doesnít seem to have any pellicle on it and it is still slowly fermenting away in my cold house (~55-58F). Perhaps the cold is part of the reason for the lack of infection?

I scooped a bit of the yeast brain out with a toothpick and gave it a taste, it definitely tastes like yeast. Any yeast geniuses out there know if this is Brett. or not?

Either way I think I will be saving this and brewing something with it.

Certainly sounds like Brett (I can't see your pictures), there are other "oxidative yeast" strains, but I believe they are active earlier in the fermentation . Pellicles form in response to oxygen, so leaving it open is what is causing the different appearance than the main batch. There probably are other microbes falling in there, but since you used sugar water and not malt extract there wouldn't be much to ferment (although eventually you'll get something that will convert the ethanol into acetic acid).

I figure I'm very likely to get some acetic alcohol bacteria eventually since I also make Kombucha.

I've changed the location of the hosted images so you should be able to see them now.

If I scoop off this pellicle from the surface am I likely to be separating the Brett yeast from any other strains that may be in there or is that pretty much hopeless without a microscope and mad pipette skills?

Wow... that is one of the weirdest and coolest pellicles I've seen. The Brett I've dealt with tends to look more powdery, that could just be a different strain, or another microbe completely. It also may just be the picture.

The pellicle should have more of the microbe in question, but it won't be a pure culture.

I wish you were closer to me so I could streak this stuff using pure culturing techniques. I'm actually interning at a brewery at the moment so doing yeast tests and other things are right up my alley.

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Bierhouse15, I gave the pellicle a taste and it tastes pretty yeasty, I'm not really a yeast connoisseur so I can't really describe any particulars.

Jessup, I've already made beer with this and it turned out well.

It attenuates really well, the final gravity of my first batch was 1.000 (OG 1.050)
For testing the yeast I did a one gallon batch of a very light tasting beer (maybe it could be considered a cream ale) so I could detect any weirdness imparted by the yeast. On pour there is a fairly foamy head (almost looks like champagne) that dissipates fairly quickly it has a somewhat grassy or herbal aroma to it though that doesn't seem to come through in the flavor which is very clean and crisp. I don't detect any particular off flavors though you can tell that it is a wild yeast but I'm not sure how to describe particularly why.

I've recently brewed a 5 gallon batch of Belgian Wit style beer and it is currently fermenting with this yeast.